This project represents a direct continuation of our studies on the nature of the blood-ocular barrier and blood-brain barrier and on the physiological and pathological factors that control and/or alter the chemical composition of intraocular and cerebrospinal fluids. Over the next five years we will focus on 1) a better definition of the prostaglandin transport process and 2) on experimental and pathological factors that affect the chemical composition of intraocular fluids. 1) The mechanism and specificity of prostaglandin (PG) transport will be studied in vitro using 3H-PG uptake by anterior uvea, choroid plexus and kidney cortex. Transmembrane PG transport will be studied on bladder-like preparations of the rabbit vagina or on the membrane-like preparation of the anterior uvea. We will also study the effects of systemically administered PG transport inhibitors on the passage of PGs across the blood-ocular and blood-brain barriers on the systemic prostaglandin metabolism and excretion. 2) The effects of experimental uveitis (induced by endotoxin, foreign proteins, nitrogen mustard or x-ray) on the chemical composition of IOFs, and on the transport capacity of the ciliary processes and pigment epithelium will be investigated. Other pathological factors that will be studied at a later phase of this project include acute total or chronic partial asphyxia or ischemia, ocular hypertension and the effects of drugs, hormones and toxic substances on blood-ocular fluid barrier and transport functions.